SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8711e176de050a4f7013a0897043fec3acbd981d768036d2c01cb7f94db182c' 
  AND token = 'vYsBECMFAi5V0iBE2krzV45cCXBkGEwE4wgWc58kUUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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