SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac21f4e484545807f8180ecb07462fa4305fba45d664bd8ea748d04ad4c5020a' 
  AND token = 'vBx3GFblmQKlD64o3XqtmnbAzl9rZbEl1FoQjeo/59c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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