SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cfd5fcdb4241003785fd226bec1541cebe05f1bb3ebacb1c60a989e68b87fa6' 
  AND token = 'e5MRtftIWaefiAKXZblumBLOGVUzBnmCltnPURGqLrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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