SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6fdcbb6315af0dabf66405e238093be0d2a106f33116a9ec9d56fb89da04f7c' 
  AND token = 'pPG1oENXqvtJm16h9dpdpd0s5/+Qdd74B/vNdv9YZlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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