SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e5bf408c9cf8220538993a42ece37a4647f1f7e393324c488d6003818f995f' 
  AND token = 'b0+zlHPC5QElX8YoVnEJFwzqSoSEMcNGhNfkqaBB/D4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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