SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340cae714afa56251a660abbf4a19ff62249493f33b1c7df4421698475704977' 
  AND token = 'jlqVeI++vALYDUCcW9eZ9BAmR3m/C1iu5EVSQrjYxKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}