SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4316f665f971a17252af9a262bc1bd448bdfffda154481451093833dff92f5b9' 
  AND token = 'zxxmto/5bFM4jL+tsrlPdk2LJMGNgSvYpeMmsCqPaxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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