SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40306ddb3f6e11601bff3f9275e1c08c2e5ecc1a2c41d3408ac699abcf056713' 
  AND token = '/DDSQNZZOyrywv0ye4c0bFD4TveA0vP/MAqFRiACEMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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