SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbe15821e61c498b910c5fd31335a768d21c6b132d23f9c88a33fed94b62aa62' 
  AND token = '3GjciEMlufe/muA4Jr2Ufhg2w+ytC5pU3Mxv9UFAXXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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