SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '245dfc1a51418642475f95d490d467dfa31e2ab37ce0f75756f561ee16f2120d' 
  AND token = 'P/jv/vVR11wFymbv5iU73tmiNXdnpnKYFemoBmR8Cbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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