SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0325d6e8ab4ea90d8d21c15ea30a5a0cece0d2039573d7eec3a531d6f7b42ef' 
  AND token = 'ZgAL+GXrLla+iZP7Xrp4nSbGk1eXWvHjYTyKnc/7xY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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