SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a9f0de275d404c53dfd5c17a054ea39a42d97ef5995f2fdb75217834b3fc698' 
  AND token = '2/TLMZfaZ0YyQxSmjI8Lyd79Xg/CaPvzZbtEPBDEEOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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