SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f42043e4f9fb61f2cb4f9541d35696b496b292179814fcc1e9f2a8c94a2a0e70' 
  AND token = 'mPUjomtQifbdvRtblyCsnw3suJmDLV3f61hGpPOz96Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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