SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21f54d46f6b5d157e75356d181c767b26c16bacaed5154d291d15c751d624fd1' 
  AND token = 'bXMrqXjqQaGLuF873kmSq+HWKANrjq9GAxdAAw6WDV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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