SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb109c21794073fc15affedcaa40ee0de3b4d613d8563c6779e6d9759dd01635' 
  AND token = 'KeApKXVyoTEFtc4+orsV7UHcVsKStw1EamG2vRhT/Z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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