SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b1938869c6980ee5bfceae454a8761148144e6ff10d803693c0edf546540403' 
  AND token = 'IAFIZ0DeUSPAB3prQRzB9lw5C/bSH0GSlqzPbRsr/4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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