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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '508864aa3bc354f3c21d52d8236b80269d8cbc01732ecde65eb5a40d7036c8d5' 
  AND token = 'z8wIpw17xCwQVeWSS/XB3RDevHL5JSyAqiwRTWxa2kQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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