SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d12cd0ced062bbe2e69e425245669268dd85bd8b6d6daece5bb5a1953506af4' 
  AND token = '7cbslV8zhqYJWkMAiXgFPL6WIYrHdoG6N4XMJ9aG3I8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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