SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8734f6321c10a580ceaf826ea13a3371b678198fcd74216cb52c7c1b111a1ffa' 
  AND token = '8oRJ5fIcPwm0W8JLnOp5W8WE5fXkXYL0vXCGjLjdVmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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