SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8fd3a06c8f05b9636012d07931b416cac8d37da31d29917b1891e617ce8c35a' 
  AND token = 'eHQl7oALHN0gehvO52AONy8J+bUNDmxDVEVGg1G2XBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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