SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2347842669bc3f897a0e72d556ec824418672614505ff7c28370a1d65a69c64' 
  AND token = '0yv3GCupLDpUM4JWUMakYFcnUWlQjCLXuthMD8KZaGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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