SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6401adc2861aa4d656924b1afa0801dd789f1fa5b4ea74915eefa9ff9d803da1' 
  AND token = 'Kg2rhpulw3wT5nl158K9fb8GuKIIlCf5CaLZyLkxGYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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