SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c138619ffa9adac72be884a9c736642af160a9174f5296007415175d9216d41' 
  AND token = 'Eo2ixmmU+9nnvX2r4BFDhZbz0IxNU5vymnRDNErNqF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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