SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74a275bb17750cb48fc099d6b66ca0d7358be184a224267e385248d451624a29' 
  AND token = '7tbLzcYYfdptMPVGEQptM/xMShnzqTBpAllPrvR5id4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}