SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76e598a1ddcd3bdc980c81e52c1d7f88826e83593f30147a87033919fd522155' 
  AND token = 'ljdAIas2EeZKkVAy0Ki1moHQ2ixzN1U8b0kPJkNIxKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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