SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1978cd0bff71655724187c142554042a89264abf055ce22a5c81af38d4a7bdfb' 
  AND token = 's52cqG4gnvPINECRHTlCOmTSxehtwxvVyduv898ozS4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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