SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f999a46403a85016d1fe20c78ff5f99d989fce4cfe3f40fd411851f6554ac0b' 
  AND token = 'EmpCL7sP8N9Qi4fqVoMrPyV29SlCF3CCCUsQ69HFEL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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