SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f9f514af8ca8513c329087c0cb2fdd9a0dd94da76a48edbdc5cc637570bd416' 
  AND token = 'SEA2b8hyrNpyexnBkW8lnofVKgeJ3Ukjrc6h8HyV2xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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