SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5a8955edf5f32d8783dd880fedb3568d6352c1448385dcc530777e5be2cee58' 
  AND token = 'mZCn6bxYuA1dgwdXf6EVL1jyjt9LOaiJgBYrlME3OvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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