SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c223ef173aae3186e34325577f2dccd65be89010f6d8f8719b19e5341b1bd6' 
  AND token = 'k6EP+IsOsEg01wESO/ziKG52zgtmeV6Tel+vgHHZSj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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