SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7757c050327825064ec5163e6427000feabe65dd6a6d13bf94c8e25a7ecf572e' 
  AND token = 'z5jaxvXAtmL4DckriT4m5QV8guasflBDD7m/1bWnDgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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