SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb7816365fb663c2858c487b4f433307fd8b419c5e7dd0d1ed5446938b1679d2' 
  AND token = 'AurTlFqVa5jIvf4bi+mwTE5L1BJQYW6Cn/xskxXx7aY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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