SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c268b755fe970718ed773e93948af723a6638233caed0d23d19437c2f121a63' 
  AND token = 'OyxJd1iA7NIRhJelI7XoYPAeg1CeGWwls0LMez5YfqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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