SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1048554b83e231cd3bb250ea6a6e29586c3b31e25b0363632383cb45889964e' 
  AND token = 'nwz9n0DBNqcS0njCQClwmp+N1PoPGMeTtK1JezOZykY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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