SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1796b6f523a85ffce304a22e9935613bc870305f602987318ef5fecd92f1c6a4' 
  AND token = 'CJimvab1+uY07kCJ3Z9/U2ai7Cw71pAxiIWaxRUwfyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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