SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '157d257c947171c37bc2acaeea4f7f3c7e51aa3194507d11b8fb9fc2c0ce8bac' 
  AND token = 'kqSaAik0+/raOch8xm1AjtKMiZlS3yQzyvfLGibn/PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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