SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '282635e1774b181abf339a82457a472fb3158bccf4fee25ad92006f36479558a' 
  AND token = '6tGVkVuopbaNPZX3yt6SnMq6xc6JrYOWof0khlHfE2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}