SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39e7091553801f0991853fa3b3dde455929fc38472e097bfc41160e2f610f774' 
  AND token = '4zPfLl6BiFl2n5oGcjmTqdwJmujLVAYFry8oJYGaRWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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