SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb84bc3af5beef399440112667d347f970ab5629a331d4739688dac8cc9fddfb' 
  AND token = '14JrHKkiLtAMYogEz/1lZO+zWxGDW+zJXQLimw/l03Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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