SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '327c65121cebff75674244c9a0828bf5b7df9dc460eeb822fcdd085c68177325' 
  AND token = '0lvcIzWVEOcL/MuJCgNDT0oBVlOl4GaBITJXgoDg47w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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