SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd21795e0fc915789c77e50e754dc249b69050bd80f95ce66b57dbd0db992553' 
  AND token = 'G3poI4j59kKRaKTzO1olhZBGyYC3yhD+wtZpeXEjtqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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