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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b335ff5aa7b91d9cbb3f904de4842de7d22ec2643359f637ca861d4835c09b69' 
  AND token = '8MIzdHb5aqq2KfqhPJnVxUMrd+bMVVlT+ynxeoQlW6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}