SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '644af3a6442aa85cc64a5877129658c8a56d39f027b840cfede84b36940530de' 
  AND token = 'LQHwFqIIbx9dFutzkUTs+AOnlD+NdzMlE1V+6V67SlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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