SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd3c52e0104b97768f27385e103e5528430a3764b681902f910334a7c9a2b6f4' 
  AND token = 'HzOvWNvPDqFm5P357e+YO68i3HuubcLiFWNABGnh7nA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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