SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18be875821cf95605a46faefbd53ed4decd18b989f381492506cb0e0aa10ee61' 
  AND token = 'fG3HAMRGU7kSB5QZ2r+yiGtYUE+Cadjj1n2kysU4c74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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