SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7b173e979d23b958c4023ac0c4f509eb7afff360749103d0ce23e6c3944973a' 
  AND token = 'u+SC/Reh/D1C1Fqm5CZQCVqWAzt8yQJQ5Zrph19rOwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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