SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd99f3c6418273ef2a934c890bb7f666bacb6cd68d36ed2c6c299d7fe1cbd1a06' 
  AND token = 'P7AFrcFvhG8xy5WJfZewljzuVk4AYYGW/LpTlpDrdyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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