SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2698a795e4342ddfbe016d28389d700168653ca7b675ae4d416049a6cf99b77' 
  AND token = 'rx6R2/UfWDAz8i4nYTVlywuMagSZm82n/gXTMhsjR1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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