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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba9a543c4e3b7d5a9d952ee60d4272c6c5b5520715eacd14a2bf4aac0abe6d51' 
  AND token = 't4daZP876DhQA/hm5+dx3/FiKT1CYWlJhevS9xTyR5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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