SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9890ffa7c0036c69de8f63f1a1cee18140d684a07a00707e8cad9acac820000f' 
  AND token = 'jLCeMMEC+EpKY28nv4jHQfVJI2OoawEDNstHsUwerdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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