SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87844172c8bd5525213e511e92db23cc43085cc0de04cf5b96dc7251b8e5a07d' 
  AND token = 'yKI1X38xDE1SFvuyUTM2Mp3SpgiBsg2RdSFlnZi/vtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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