SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2c0e95879535465f53bf12458455f3a204c342537393df670ae9213ebde04ac' 
  AND token = '5iIkmSTpJspLFQnbHM5Vl4+RwoxPrtujPgZDdQbtWBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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