SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c63480c5a4c9cd105fd75c7e5639754024e0e5a51594845da9c48a73750d0da5' 
  AND token = 'gLKsauA/zRZd/hrScRm8zOTEYaAwOOLYMKbELqBDmO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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