SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28fb7e890e376681b7b19f604113a28557da222f2dc24e875acf4a6c1f44adbb' 
  AND token = 'qgm3UawBBdYAFPNFGyRA8rCQdQ8tgPJtHvqQg/iGc7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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