SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e879b1536918bd2e554c29bcf88f65074d7383c6f894d8363f34d35ff3efd9' 
  AND token = 'MgKytJoxqDhWxhYlfH/YX3ri70kgchUgDmUB93CBGK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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