SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5fe5d4f8b2f52d870fde91604ccc53f412220c086eda9359abb471a5da3c707' 
  AND token = 'iQSRmaluwHCO8VLIKGtSfdOE2VUO5HAf3W0cdWJJlkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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