SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52641a2fe6d0529f3a9691b3b821efa80a8d04acdddd213acada54b74c973e36' 
  AND token = 'W1ZQaSVWgOLnWgNOWZ4aVkKtk5NrA73VoNkUqT5dEgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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