SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '588ac67dc9e85db28feccfa4fd56b3990287dac3c26745dc885645e270a50423' 
  AND token = '7BFSHfiibfvCanar02o5WO7ZDcrrR5i1H9+k10dMtvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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