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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f63a8f216767839edbd566b61dfc8046358995024964d4e82a6cf198fde5ee3f' 
  AND token = 'l4aLfk9Kv1ESmfCcmEwZNAhSbMMaM/ZZDq/4VyS+Qgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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