SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df9d2326eb936aae0cf32679fac3ed656dc22f2146d1c75d05cde693c1cddd60' 
  AND token = 'pZMOYwTchm+GtjQ9CyyjTMm5XIel69VZOrtEAJ8VZlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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