SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b107351dfc4112466a844b15256ff689602c52b7044cb79665edd03ec96cd78' 
  AND token = 'Ux1QubmSVE3koRk/+IeB63h2Tnm1bKQV6dsOnKXWjdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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