SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39cec294d42a840b1e1a16d74779450d1d1a301f9e2d06872f524e219846a333' 
  AND token = '+IEVokZO4d4zxCjvkmqhYZvfkUAHttDS0FSEkONDNzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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