SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fdbf49b3b446359bfb515fae6239808f2dbfcb6f03be237cedc8985e886999e' 
  AND token = 'SfG1XEjMdZCLV+/sWZEGXSOCW0DaG6oWD6E/gFbWGQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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